The pilot of a gyrocopter whose rotor sliced through the head of a hunt supporter during an angry confrontation as he refuelled was cleared of manslaughter today. Bryan Griffiths, an animal rights enthusiast who had been monitoring the Warwickshire Hunt from the air for possible breaches of the Hunting Act, was acquitted after seven-and-a-half hours.

There were gasps and a ripple of applause from the public gallery at Birmingham crown court as the jury foreman gave the verdict. Griffiths, 55, showed no reaction and left court without commenting.

The two-week trial heard how Griffiths was ambushed in March last year at Long Marston airfield, near Stratford-upon-Avon, as part of a plan by hunt organisers, who were on their last outing of the season and who were fed up with the aircraft's constant presence. A long-standing follower of the hunt, 48-year-old Trevor Morse, followed the gyrocopter to the airfield and drove his Land Rover alongside.

The court heard that he then stood in front of the plane, as Griffiths manoeuvred to find a gap to take off, with the tail rotor whirring at 200mph. A video taken by a fuel handler at the airfield showed the blade suddenly strike Morse, a self-employed gardener, killing him instantly.

On the film's soundtrack, a voice first shouted to Morse: "You are obstructing him taking off, you have no right to do that, you have no right to do that." After a pause, the jury then saw a clip of Morse's body lying on the ground, at the start of a 15-minute wait for an ambulance, as another voice said: "Oh dear, the twat didn't stand clear of it."

Another hunt supporter who was with Morse, Julie Sargeant, broke down in tears as she described how she had got back into the Land Rover to avoid trouble.

Describing Morse as "Mr Nice Guy" and evidently still shocked by the incident, she said: "He just stood there. He just stood there."

The court heard Griffiths had been scared of violence from hunt supporters, and shortly before the standoff had told Michael Tipping, a plane spotter at the airfield, he feared a gang was coming to attack him. Tipping's non-partisan evidence, as someone without strong views on hunting, portrayed Morse as "intrusive and aggressive".

Tipping told James Wood QC, defending, that he had felt threatened by the hunt supporter, who had started taking photographs of him and his car. He said he would have been frightened "particularly if I'd argued with him. Which is why I didn't argue with him." Tipping added that Griffiths had told him that he had been shot at from the ground three times.

Caroline Morse, Mr Morse's partner of 23 years, said in a statement released by Warwickshire police: "I am absolutely devastated by this result. I am neither pro- nor anti-hunt. It has been a long 12 months since Trevor's tragic death and we are still coming to terms with our loss."

Tributes have appeared on hunt websites to Morse, who helped look after birds of prey which allow hunts to use a legal loophole allowing falconry.

Judy Gilbert, a friend of Griffiths who also monitors hunts, said after the verdict: "We just wanted to say how absolutely delighted and relieved we are that he has been found not guilty. Of course we always knew ourselves that he was never guilty of any crime and he certainly didn't mean anybody any harm.

"It's just so sad to us that this tragedy has happened because people want to chase animals for sport and kill them, when it has been made illegal by our parliament. I'm sure he's absolutely devastated it happened. He's a decent man, he's one of the most decent, honest, straight people that I have ever met in my life and it was just sad to see him go through this terrible trauma for the last year."

Det Chief Insp Peter Hill of Wawickshire police said: "This case had to be heard. The jury has listened to all the evidence and I respect the verdict they have returned."